{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:33:16Z","timestamp":1760243596966,"version":"build-2065373602"},"reference-count":18,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2012,4,13]],"date-time":"2012-04-13T00:00:00Z","timestamp":1334275200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>It has been suggested heuristically by Unruh and Wald, and independently by Page, that at given energy and volume, thermal radiation has the largest entropy. The suggestion leads to the corresponding universal bound on entropy of physical systems. Using a gedanken experiment we show that the bound follows from the Second Law of Thermodynamics if the CPT symmetry is assumed and a general condition on matter holds. The experiment suggests that a wide class of Lorentz invariant local quantum field theories obeys a bound on the density of states.<\/jats:p>","DOI":"10.3390\/e14040736","type":"journal-article","created":{"date-parts":[[2012,4,13]],"date-time":"2012-04-13T11:38:42Z","timestamp":1334317122000},"page":"736-741","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Radiation Entropy Bound from the Second Law of Thermodynamics"],"prefix":"10.3390","volume":"14","author":[{"given":"Itzhak","family":"Fouxon","sequence":"first","affiliation":[{"name":"Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2012,4,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"287","DOI":"10.1103\/PhysRevD.23.287","article-title":"Universal upper bound on the entropy-to-energy ratio for bounded systems","volume":"23","author":"Bekenstein","year":"1981","journal-title":"Phys. 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